PROJECT SUMMARY/ABSTRACT One in three older Americans is prescribed a strong anticholinergic medication, despite anticholinergics being contraindicated for older adults on the basis of considerable evidence linking use of anticholinergics with cognitive impairment, Alzheimer's disease, and related dementias. National entities including the National Academy of Medicine call for research on interventions to reduce anticholinergic exposure among older adults, as a risk factor for Alzheimer's disease that is amenable to behavioral intervention. We know of no intervention studies directly targeting consumers of anticholinergics. In prior work, we demonstrated the ability to reduce anticholinergics use by older adults by having a geriatrician deliver the intervention directly to consumers. While successful in reducing the proportion of anticholinergic users by 52%, this and other interventions delivered by a physician or pharmacist are expensive and not scalable. Our proposed study tests the efficacy of a consumer intervention, the digital Brain Safe mobile app, a low- cost, scalable mobile application designed by our interdisciplinary team of experts on medication safety, aging, and user-centered design of technology for older adults. The intervention integrates a personalized anticholinergic risk calculator, targeted multimedia content, and a conversation starter to help patients to self- initiate anticholinergic de-prescribing with a clinician. In a feasibility trial of Brain Safe with 17 older adults using at least one strong anticholinergic, 100% of participants reported feeling better informed about medication safety after using Brain Safe, 94% reported planning to speak to a physician about their anticholinergic risk, and 88% did so (confirmed by physician in 82% of cases). Usability testing with 34 older adults showed an ?Excellent? usability grade (median System Usability Score = 82.5). In the proposed study, a randomized controlled trial is planned to primarily test the impact of Brain Safe on prescription anticholinergic exposure among older adults at 12 months after intervention. Secondarily, we will test the impact of Brain Safe on cognitive function and health-related quality of life at 12 months. We will explore early effects of Brain Safe on these primary and secondary outcomes at 6 months. Older adult participants will be randomized to receive Brain Safe or an attention control app (WebMD Health Assessment) for 12 months. A total of 700 participants will be enrolled over a 42-month period from a large pool of patients receiving primary healthcare at Eskenazi Health and Indiana University Health. Assessments will be performed at baseline, 6, and 12 months. We will use t tests and mixed effects models to test hypotheses comparing the two conditions on exposure to strong anticholinergics at 12 months. The trial is powered on the primary outcome of anticholinergic exposure at 12 months, assessed by dispensing records. Because anticholinergic drug exposure is a modifiable risk factor for Alzheimer's disease and related dementias, scalable interventions to reduce older adult exposure to anticholinergics are urgently needed.